In this blog post, we explore the roles of structure, aerodynamics, propulsion, and control—the core elements of aerospace engineering—and why they are essential for designing airplanes and rockets.
Before introducing what aerospace engineering is, we must first understand engineering itself. Since aeronautical engineering belongs to the College of Engineering, it is a branch of engineering. Engineering is not merely a collection of techniques; it is the result of combining human creative thinking with scientific principles. Engineering plays an essential role in our daily lives. The electronic devices, automobiles, buildings, and even medical equipment we use are all products of engineering. Engineering can be defined as the artificial creation of objects that did not exist in nature. So, can we call primitive people making stone axes engineering? No, we cannot. Engineering is not about making things haphazardly; it requires systematic creation using natural science, particularly mechanics. Mechanics, as the name suggests, is the science of force, calculating how an object changes and what state it enters when force is applied to it. Performing these force calculations is crucial in engineering. For instance, ancient Roman architects employed mechanical principles when designing and constructing massive amphitheaters. They didn’t just stack stones; they calculated weight and pressure to ensure structural stability. Modern engineers similarly design safe and efficient structures through complex calculations and simulations. A building designer must calculate the various forces acting on the structure. They must account for the building’s weight, wind strength, ground vibrations, and more, designing it to withstand these forces without collapsing. Thus, the discipline of creating artificial objects based on mechanical knowledge is engineering.
Now, let’s explore aerospace engineering. Aerospace engineering, meaning the engineering of aviation and space, involves creating artificial objects for use in the sky and space based on mechanical knowledge. What kinds of artificial objects are used in the sky and space? These include airplanes, helicopters, rockets, missiles, and satellites. Aerospace engineering represents the pinnacle of modern technology, and significant research and development in this field is being conducted worldwide. Artificial satellites handle global communications, and the GPS system has become an indispensable tool in our daily lives. Without aerospace engineering, the development of these technologies would not have been possible. So, what mechanical knowledge is needed to create them? Four major areas can be identified: structural mechanics, aerodynamics, propulsion mechanics, and control engineering. These are referred to as the four major fields of aerospace engineering. To explain what each of these fields does, let’s consider the scenario of building an airplane.
To build an airplane, you fundamentally need its structure. You’ll need components like wings to enable flight, a fuselage to carry passengers and cargo, and tail surfaces to maintain balance. To achieve this, calculations are needed to determine how much force the aircraft’s frame can withstand without breaking, and if it doesn’t break, how much it will deform. Furthermore, how long it can endure under these conditions is also crucial. An aircraft consists of numerous components, and it is vital to understand how each component withstands and distributes specific forces. It is especially essential to design materials and structures capable of withstanding the pressure and temperature generated during high-speed flight. Therefore, structural mechanics, the subject that calculates these factors, is necessary. Unlike other man-made objects, aircraft incorporate highly irregular structures like wings. Consequently, in aeronautical engineering, structural mechanics places significant emphasis on calculating forces acting on irregular shapes, distinguishing it from structural mechanics in other engineering fields.
Suppose we have constructed an aircraft’s structure; the next critical aspect is flight itself. An aircraft utilizes its wings to create a pressure difference above and below the wing surface. This pressure difference generates a force that lifts the aircraft, known as lift. Aerodynamics is the discipline that studies this lift. Aerodynamics, meaning the mechanics of air, is the science that calculates all types of forces generated by wind movement around the wing, including lift. The forces acting on a wing vary depending on its shape. A primary goal of aerodynamics is to develop wing shapes that generate the greatest possible lift. Aerodynamics plays a crucial role not only in making an airplane fly but also in maximizing its efficiency. Examples include designing wings to fly farther distances while consuming less fuel and optimizing wing shapes to reduce noise.
Once an aircraft can fly, the next requirement is forward motion, meaning propulsion is needed. Means for an aircraft to gain propulsion include propellers, jet engines, and rocket engines. The engineering that designs these propulsion systems is called propulsion engineering, based on thermodynamics and fluid mechanics. Thermodynamics is the study of methods to generate power using heat obtained from fuel. Fluid mechanics is the study of the flow of fluids, such as the fuel and air required for combustion. Propulsion systems fundamentally mix compressed air with fuel, combust it, and then use the heat generated to create thrust. The advancement of propulsion engineering is one of the core elements of aerospace engineering. Recent research focuses on developing engines that use environmentally friendly fuels to reduce carbon dioxide emissions while simultaneously providing more powerful thrust. Therefore, both of these dynamics are essential in propulsion engineering.
Now, airplanes can fly and even move forward. So, the final necessity is controlling the airplane. Here, control means guiding an object to achieve a desired state. To do this, we must first know the object’s current state, which is where sensors come in. Sensors detect external stimuli like temperature, pressure, speed, tilt, etc., and convert them into electrical signals. This allows us to know the object’s state. Once the object’s state is known, the next step is to move the object to the desired state. The component that performs this role is called an actuator. Together, the sensor and actuator form a controller, and designing this controller is precisely the task of control engineering. Control engineering plays a pivotal role not only in aircraft but also in diverse fields like autonomous vehicles and drones. The principles of control engineering are essential for the stable operation of complex systems and significantly contribute to ensuring flight safety in aerospace engineering.
This concludes the explanation of the four major fields of aerospace engineering: structure, aerodynamics, propulsion, and control. You might wonder if using only airplanes as examples implies rockets operate under different dynamics. This is not the case. Rockets also travel within the atmosphere like airplanes until they reach space. The forces acting on a rocket within the atmosphere are similar to those on an airplane. However, the situation changes completely once they exit the atmosphere. Movement in zero gravity and propulsion in space must follow entirely different principles, leading to the new field of space dynamics. Therefore, rockets are not fundamentally different from airplanes. The only difference is that after reaching space, a rocket’s trajectory must be calculated based on universal gravitation. Thus, both airplanes and rockets are fundamentally designed based on these four fundamental principles of dynamics.
